The present disclosure relates to a reception apparatus, and more particularly to a reception apparatus capable of suppressing an increase in the circuit scale while reducing an external noise therein, the reception apparatus receiving a plurality of transmission signals in different frequency bands.
In recent years, global positioning system (GPS) functions are mounted in various electronic apparatuses including a car navigation system, a portable communication apparatus such as a cellular phone, a digital still camera, and the like. A GPS receiver that realizes the GPS function receives, for example, a transmission signal called a GPS L1 C/A code that is transmitted from four or more GPS satellites and determines a position based on the received transmission signal.
In this case, a transmission signal transmitted from each GPS satellite is a signal obtained by performing a binary phase shift keying (BPSK) modulation on a carrier of 1575.42 MHz, based on a spectrum spread signal that is obtained by subjecting data of 50 bps to a spectrum spread using a Gold code where a code length is 1023 and a chip rate is at 1.023 MHz.
Meanwhile, such an electronic apparatus having a GPS function has multifunction and high performance, and unnecessary radiation generated in the electronic apparatus increases. The unnecessary radiation generated in the electronic apparatus corresponds to a kind of an external noise for a GPS receiver of the electronic apparatus. Representative examples that become factors of the external noise due to the unnecessary radiation may include a clock signal that interferes through coupling or space between wiring lines in the electronic apparatus, harmonics due to a high speed signal that passes through a data bus or the like, a variation in load of a circuit, and a variation in power due to a switching regulator. In view of this, a GPS reception apparatus provided with a noise removing function of removing such an external noise is proposed (see, for example, Japanese Patent Application Laid-open No. 2009-206603 (hereinafter, referred to as Patent Document 1)).
By the way, a positioning system that determines a self-position and a speed of a moving body or the like includes, in addition to the GPS, a global orbiting navigation satellite system (GLONASS) developed and operated in Russia and the like. Therefore, a reception apparatus that receives two transmission signals for the GPS and the GLONASS is also proposed (see, for example, Japanese Patent Application Laid-open No. HEI 7-128423 (hereinafter, referred to as Patent Document 2)). In this case, the carrier frequency of the transmission signal of the GLONASS is, for example, 1602.00 MHz and different from the frequency band of the transmission signal of the GPS, and hence it is necessary to process the GPS signal and the GLONASS signal through separated signal paths.